In the case of a craft, such as high performance aircraft, control personnel such as the pilot or crew member are a limiting factor during flight. If cerebral dysfunction of such personnel were to occur and go undetected, the result could be catastrophic loss of life and/or property--not only involving the craft itself, but the surrounding environment should the craft go out of proper control. The extremely rapid performance characteristics of modern, high speed aircraft calls for almost instantaneous corrective control action to avert tragedy. Where a craft encounters hostile forces, temporary evasive action may be required of a degree accompanied by high-G stress where the pilot blacks out--temporarily. Here again almost instantaneous control action is required to conduct the desired evasive action. It may be desirable to have control either returned to the pilot following recovery from the black out, or the aircraft maneuvered to a desired status or destination.
Technology exists for monitoring selected characteristics of the human body in vivo. U.S. Pat. No. 4,281,645 describes embodiments of a device capable of "in vivo, in situ, non-invasive, atraumatic and continuous monitoring of three parameters of crucial significance related to organ metabolism' where "information on the state of circulatory adequacy and oxygen sufficiency are needed". Columns 11-14 of this patent describe details of the measurements of these metabolic parameters. Measurement of any one or any combination of these is useful in detecting pilot blackout and recovery from blackout. U.S. Pat. No. 4,380,240 issued to Frans F. Jobsis et al, there is described a spectrophotometric method directed to non-invasive, continuous, atraumatic, in vivo, in situ monitoring of metabolism in a body organ. It is generally known that metabolism and more particularly oxygen sufficiency and adequacy of utilization are parameters of fundamental importance in accessing the function of any body organ. This is made self-evident when one considers that the energy provision for tissue function is underwritten for better than 94 percent by oxidative reactions involving the reduction of O.sub.2 to H.sub.2 O. In the absence of sufficient oxygen, this process becomes impaired with a corresponding impairment in organ function. In instances of extensive oxygen deprivation, over a period of time the organ loses viability and as a result the individual often has the same fate.
Although all organs are adversely affected by oxygen insufficiency, perhaps the problem is most acute in the case of the brain because of its exquisite sensitivity with respect to oxygen demand and its complete dependence on oxidative metabolism for proper function and viability. For example, an absence of adequate oxygen delivery by blood to the brain for more than a dozen seconds produces dysfunction and an absence for longer than a few minutes spells irreversible damage. A less acute impairment of oxygen availiability leads to a gradual loss in brain function, expecially with respect to the higher centers of the cerebral cortex.
The NIROscope is a known monitoring device which has been shown to provide accurate and immediate feedback with regard to the adequacy of cellular oxygention in the cerebral cortex. This device employs a solid-state laser, in the near-infrared spectrum and demonstrates on a heart beat to heart beat basis the level of cerebral functions as measured by oxygenation of the cytachrome c-oxidase. This enzyme system is the terminal component of the mitochondrial respiratory chain, and catalyzes greater than 95% of cellular oxygen consumption. Monitoring this enzyme provides early and accurate detection of oxygen delivery dysfunction on a cellular level, and has been shown to provide remarkable capabilities to detect brain dysfunction.
This enzyme system exhibits an absorption band betwee 800 and 900 nm, which is in the near infra-red spectrum. This band disappears when the enzyme system becomes reduced. Skin and bone are relatively transparent in this spectral region, and therefor monochromatic, or dichromatic laser radiation can be directed through intact skin and bone, and reflectance as well as absorbance can be calculated. Light from the laser is captured at the transmitting apparatus, located away from the subject. The light is delivered to the subject in two or more transmitting "optrodes" applied to the base of the skull, temporal region or frontal region. A receiving optrode is placed 4 to 6 cm lateral to the transmitting optrode. Absorbance of light in this wavelength is attributable to the cytochrome c-oxidase system. These calculations are accomplished using the Beer-Lambert Law. Corrections can be made electronically for absorbance due to hemoglobin. In view of the fact that this prior art has been discussed extensively in the patent literature and publications, for example (see U.S. Pat. Nos. 4,223,680, 4,281,645, 4,321,930, 4,380,240 and 4,510,938) such discussion will not be repeated here but the subject matter thereof is incorporated herein by reference. It is sufficient to state that a near infra-red oxygen sufficiency scope (NIRO-scope) exists and is employed to monitor the adequacy of oxygen delivery to brain tissue. Means are provided for securing to the brain, a light source housing and light detector housing used for monitoring metabolism.
In a preferred embodiment this apparatus is mounted on the pilots head under his helmet and the input and output signals are coupled by means of fiber optic cables to a light source and processing circuitry. See U.S. Pat. No. 4,510,938 issued to Frans F. Jobsis for a more detailed discussion of the considerations involved. It is sufficient for our purposes to state that this system or other similar sensing systems provide rapid detection of G-induced cerebral hypoxia, oxygen delivery hypoxia, or other pilot failure that would otherwise go undetected resulting in pilot/aircraft loss. Other less common problems such as pilot death, stroke, or injury due to foreign object damage would be detected. Non-high performance applications might include detection of hypoxia in high altitude transport due to oxygen failure or decompression.
Aircraft may be controlled manually or control may be transferred to an automatic control system in response to appropriate signals. For example, U.S. Pat. No. 3,337,163 describes an arrangement where control is immediately restored to the automatic flight control system whenever the pilot removes his hands from the manual control. Autopilots for maneuvering aircraft which can be locally or remotely engaged and disengaged for operation are known in the art.